1. Field of the Invention
This invention relates to a failure detection device, a failure detection system and a failure detection method used with a passenger vehicle, an autotruck, a bus and the like.
2. Description of the Related Art
For example, Japanese Patent Application Publication No. 2006-315427 (JP-A-2006-315427) describes a vehicle in which an ECU (Electronic Control Unit) monitors failures of on-board devices that realize various control operations of the vehicle, such as sensors, an engine, and a brake. In the vehicle, a system that performs a specific vehicle control operation includes an ECU_A, a sensor that is connected to the ECU_A, and an ECU_B and an ECU_C that are connected to the ECU_A using a communication standard such as CAN (Controller Area Network). A vehicle navigation ECU is also provided that is connected to the system via CAN and monitors the system.
In this system, when a disconnection failure occurs between the sensor and the ECU_A, the ECU_A sends a DTC (Diagnostic Trouble Code) indicating the failure (hereinafter “DTC of failure”) to the vehicle navigation ECU, and sends fail information to the ECU_B. Upon receiving the fail information, the ECU_B sends a DTC indicating the reception of the fail information (hereinafter, “DTC of failure reception”) to the vehicle navigation ECU.
Similarly, the ECU_B sends the fail information to the ECU_C. Upon receiving the fail information, the ECU_C sends a DTC of failure reception to the vehicle navigation ECU. Thus, the vehicle navigation ECU collects both the DTC of failure and the DTC of failure reception to monitor the operation of the system, transmits both the DTCs to a center on a road side (hereinafter “roadside center”) via a base station and network. The center on the road side analyzes, for example, failed parts and failure frequency of each motor vehicle line based on both the DTCs, and creates a failure database. The failure database may be used for repair of vehicles at car dealers.
In the above-described system, because both the DTC of failure and the DTC of failure reception are transmitted to the roadside center, the communication loads and costs using the network and base stations increase. Moreover, the DTC of failure reception sent by the above-described ECU_B or ECU_C is a DTC indicating a passive failure arising from the ECU_A rather than indicating the failure arising from the ECU_B or the ECU_C itself. Nevertheless, such DTCs are reflected in the failure database. Therefore, the accuracy of the analysis of failed parts and failure frequency may be reduced.